7-[2-(2-Aminooxazol-4-yl)-2-(oximino)acetamido cephalosporin antibiotics and intermediates therefor

ABSTRACT

Cephalosporin broad spectrum antibiotics possessing a 7β-[2-[(2-aminooxazol)-4-yl]-2-(substituted oximino)]acetamido side chain and a variety of substituents at the 3-position of the cephalosporins are claimed. Also claimed are intermediates in the synthesis of the above cephalosporin antibiotics.

This application is a division of application Ser. No. 300,140, filedSept. 8, 1981.

BACKGROUND OF THE INVENTION

This invention relates to cephalosporin antibiotic compounds andintermediates in the synthesis thereof. In particular, it relates tocephalosporin compounds substituted in the 7-position with a2-(2-aminooxazol-4-yl)-2-(substituted-oximino)acetamido group and in the3-position with a variety of substituents, such as fluoro, chloro,bromo, hydroxy, acyloxymethyl, carbamoylmethyl, substituted andunsubstituted methyl pyridinium groups and heterocyclic thiomethylgroups containing 5- and 6-membered heterocyclic rings.

In recent years, much research has been done in the area ofcephalosporins containing a 7-[2-(2-aminothiazol-4-yl]-2-(substitutedoximino)acetamido side chain, with a wide variety of substitutents inthe 3-position of the cephalosporin. Two of the most notable examples ofsuch compounds are the potent antibiotics (a) sodium7-[2-(2-aminothiazol-4-yl)-2-methoximinoacetamido]-3-acetoxy-3-cephem-4-carboxylatedisclosed by Heymes, et al. in U.S. Pat. No. 4,152,432 and (b) thecompound of the formula ##STR1## disclosed by O'Callahan et al. in U.S.Pat. No. 4,258,041.

The cephalosporin antibiotics of the instant invention possess excellentantibiotic activity while differing in structure from the aforementionedcompounds and other compounds previously disclosed.

SUMMARY OF THE INVENTION

The cephalosporin antibiotics and cephalosporin intermediates of thisinvention are represented by the following general formula A. ##STR2##wherein R₁ can be hydrogen, C₁ to C₄ alkyl or a group of the formula##STR3## wherein R' can be, e.g., hydroxy, alkoxy, amino, substitutedamino and m is 0 to 3, R₂ can be hydrogen, a pharmaceuticallyacceptable, non-toxic salt, the hydrates of said salt, or the non-toxicmetabolically labile esters thereof; R₃ can be hydrogen, halo, hydroxy,methoxy, lower acyloxyoxymethyl, a group of the formula ##STR4## amethyl pyridinium group of the formula ##STR5## or a heterocyclicthiomethyl group, wherein the heterocyclic ring can be a 5- or6-membered ring at least one nitrogen and up to 3 other heteroatomschosen from nitrogen, sulfur or oxygen.

A second aspect of this invention is an intermediate oxime side chain ofthe general formula B ##STR6## wherein R₁ is the same as in generalformula A; G is chloro, bromo, hydroxy, lower alkoxy, phenoxy, a groupof the formula --O--J wherein J is the residue of a group forming anactivated ester, or a group of the formula --O.sup.⊖ M.sup.⊕ whereinM.sup.⊕ is a monovalent cation and R₈ is hydrogen or an amino protectinggroup.

DETAILED DESCRIPTION OF THE INVENTION

This invention is directed to cephalosporin compounds of the followinggeneral formula ##STR7## This invention is also directed to anintermediate used in the synthesis of the above cephalosporin compounds.The intermediate compound has the general formula ##STR8## and forconvenience sake will be referred to in the instant application as the"oxime sidechain".

In the formulas contained in this application, the mark " " indicatesthe β-configuration and the hash line "||||" indicates theα-configuration. Also, in the formulas contained in this application thegeometrical isomer of the oxime function indicated by the followingpartial formula ##STR9## is referred to as the "Z" or "syn" isomer,while the opposite isomer, represented by the following partial formula##STR10## is referred to as the "E" or "anti" isomer.

It will be understood that since the cephalosporins and the oximesidechain intermediates of this invention are geometrical isomers, someadmixture between the Z isomer and the corresponding E isomer may occur.

The cephalosporin compounds of this invention are represented by thefollowing general formula I ##STR11## wherein:

R₁ is hydrogen, C₁ to C₄ alkyl, a carboxy-substituted alkyl orcarboxy-substituted cycloalkyl group represented by the formula##STR12##

wherein m is 0 to 3, a and b when taken separately are independentlyhydrogen or C₁ to C₃ alkyl, or when taken together with the carbon towhich they are attached form a C₃ to C₇ carbocyclic ring; R' is hydroxy,amino, C₁ to C₄ alkoxy, or --OR", where R" is a carboxy protectinggroup; or R₁ is a secondary amido group of the formula ##STR13## whereinR'" is C₁ to C₄ alkyl, phenyl or C₁ to C₃ alkyl substituted by phenyl;R₂ is hydrogen, a carboxy protecting group or a pharmaceuticallyacceptable, non-toxic salt thereof, the hydrates of said salt, or thenon-toxic metabolically labile esters thereof; R₃ is

(a) hydrogen, fluoro, bromo, chloro, hydroxy, or methoxy; or

(b) (C₂ to C₄ acyloxy)methyl; or

(c) a methyl carbamate group of the formula ##STR14## wherein R"" ishydrogen or C₁ to C₄ alkyl; or (d) a methyl pyridinium group of theformula ##STR15## wherein T is (i) hydrogen, trifluoromethyl, C₁ to C₄alkyl, C₁ to C₄ alkoxy, hydroxy, cyano, halo or hydroxymethyl; or

(ii) carboxy, C₁ -C₄ alkoxycarbonyl, C₁ to C₄ alkanoyl or C₁ to C₄alkanoyloxy; or

(iii) an amido group of the formula ##STR16## wherein c is hydrogen,methyl, ethyl or cyclopropyl and d is hydrogen, methyl or ethyl; or

(iv) a group of the formula ##STR17## wherein p is 2 to 4; providedthat: (a) when the pyridinium ring is substituted with the abovesubstituents in (iv), the pyridinium ring is additionally substitutedwith R₄, wherein R₄ is hydrogen or C₁ to C₄ alkyl; and (b) when T ishydroxy or halo T is only bonded to the 3-position of the pyridiniumring; or

(e) a heterocyclic thiomethyl group of the formula --CH₂ --S--Y, whereinY is ##STR18## wherein R₅ is hydrogen, C₁ to C₄ alkyl, --CH₂ COOH, or--CH₂ SO₃ H;

R₆ is hydrogen, C₁ to C₄ alkyl, phenyl or amino; and

R₇ is hydrogen or C₁ to C₄ alkyl;

provided that, when R₂ is hydrogen, R₃ is not hydroxy.

In the foregoing definitions of the cephalosporin compounds, the term"C₁ to C₄ alkyl" means methyl, ethyl, propyl, isopropyl, butyl,sec-butyl or tert-butyl.

The term "C₁ to C₃ alkyl" means methyl, ethyl, propyl or iso-propyl.

The term "C₁ to C₄ alkoxy" refers to methoxy, ethoxy, n-propoxy,iso-propoxy, sec-butoxy, n-butoxy and the like.

With respect to the term R₁ in Formula I, the carboxy-substituted alkylgroup (R' is hydroxy) represented by the formula ##STR19## isillustrated by carboxymethyl, 2-carboxyethyl, 1-carboxyethyl,3-carboxypropyl, 2-carboxypropyl, 4-carboxybutyl, 3-carboxypentyl,4-carboxyheptyl, 2-carboxybutyl, and the like. When a and b are takentogether, examples of the carboxy-substituted C₃ -C₇ carbocyclic ringsare 1-carboxycycloprop-1-yl, 1-carboxycyclobut-1-yl,1-carboxymethylcyclobut-1-yl, 1-carboxycyclopent-1-yl,1-carboxycyclohex-1-yl, 1-carboxycyclohep-1-yl,1-carboxyethylcyclopent-1-yl, 1-carboxypropylcyclohex-1-yl, and thelike. Examples of such groups when R' is amino are aminocarbonylmethyl,2-aminocarbonylethyl, 3-aminocarbonylpropyl, 2-aminocarbonylprop-2-yl,1-aminocarbonylcycloprop-1-yl, 1-aminocarbonylcyclohex-1-yl, and likecarboxamido substituted alkyl and cycloalkyl groups.

Examples of such groups when R' is C₁ to C₄ alkoxy areethoxycarbonylmethyl, methoxycarbonylpropyl, 2-ethoxycarbonylprop-2-yl,5-butyloxycarbonylmethyl, 3-ethoxycarbonylpropyl,1-ethoxycarbonylcyclobut-1-yl, 1-(methoxycarbonylmethyl)cyclopent-1-yl,and like groups.

It will be appreciated by those skilled in the art that when a and b inthe above formula represent different C₁ to C₃ alkyl groups, the carbonatom to which they are attached comprise a center of asymmetry. Suchcompounds are diastereometric and the present invention embracesindividual diastereomers of these compounds as well as mixtures thereof.

Illustrative of the secondary amido groups at R₁ are N-methylcarbamoyl,N-ethylcarbamoyl, N-phenylcarbamoyl, N-benzylcarbamoyl,N-(2-phenylethyl)-carbamoyl, and the like.

The term "carboxy protecting group" indicates a carboxy group which hasbeen esterified with one of the more commonly used carboxylic acidprotecting ester groups employed to block or protect the carboxylic acidfunctionality while reactions involving other functional sites of thecompound are carried out. Such carboxy protecting groups may besubsequently removed by any of the appropriate methods disclosed in theliterature, for example acid or base catalyzed hydrolysis,hydrogenolysis, and enzymatically catalyzed hydrolysis to yield the freecarboxylic acid. Examples of such carboxylic acid group include2-iodoethyl, tert-butyl, 2,2,2-trichloroethyl, 4-methoxybenzyl,4-nitrobenzyl, diphenylmethyl, 4-methoxydiphenylmethyl,4,4'-dimethoxydiphenylmethyl benzyl, trialkylsilyl,2,4,6-trimethoxybenzyl, trityl, 4-methoxytrityl, 4,4'-dimethoxytrityl,4,4',4"-trimethoxytrityl and like ester forming moieties. The nature ofsuch ester forming groups is not critical so long as the ester formedtherewith is stable under the reaction conditions of a reaction onanother position of the molecule.

In the above definition, the term "carboxy protecting group" is notexhaustively defined. The function of such groups is to protect thereactive functional groups during the preparation of the desiredproducts and then be removed without disrupting the remainder of themolecule. Many such protecting groups are well known in the art and theuse of other groups equally applicable to the synthesis of the compoundsof the present invention, such as those described in Ch. 5 of J. F. W.McOmie, "Protective Groups in Organic Chemistry", Plenum Press, 1973,will be recognized as suitable. Thus, there is no novelty orinventiveness asserted with regard to the "carboxy protecting groups"described in this specification.

The term "pharmaceutically acceptable, non-toxic salt", refers to theinorganic salts of the above compounds formed with the alkali andalkaline earth metals such as lithium, sodium, potassium, barium andcalcium, organic base salts such as ammonium, dibenzylammonium,benzylammonium, 2-hydroxyethylammonium, bis(2-hydroxyethyl)ammonium,phenylethylbenzylamine, dibenzylethylenediamine, and like salts. Otheramine salts can be formed with procaine, quinine and N-methylglusoamine,plus salts formed with basic amino acids such as glycine, ornithine,histidine, phenylglycine, lysine and arginine. These salts are useful inpreparing suitable pharmaceutical compositions of the instant compoundsfor therapeutic purposes. Because of the basic amino group in theposition of the oxazole ring moiety, the compounds of the instantinvention form acid addition salts with suitable acids such ashydrochloric acid, hydrobromic acid, phosphoric acid, sulfuric acid, theorganic sulfonic acids, e.g. methanesulfonic acid, benzenesulfonic acid,toluenesulfonic acid, and like acids. The acid addition salts also maybe used for preparing suitable pharmaceutical compositions of theinstant compounds. In addition, when R₃ is a group of the formula##STR20## the R₂ group will be a carboxy anion, in other words, themolecules will exist in the pharmaceutically acceptable betaine form.

The hydrates of the above salts are also encompassed by the scope of theinstant invention.

The term "non-toxic metabolically labile esters" refers to thosebiologically active ester forms which conduct, for example, to increasethe blood levels and prolong the efficacy of such ester compounds. Suchester groups include lower alkoxymethyl groups, e.g. methoxymethyl,ethoxymethyl, isopropoxymethyl, α-methoxyethyl, groups such as α-loweralkoxy (C₁ to C₄) ethyl; e.g. methoxyethyl, ethoxyethyl, propoxyethyl,iso-propoxyethyl, etc; C₁ to C₃ alkylthiomethyl groups, e.g.methylthiomethyl, ethylthiomethyl, isopropylthiomethyl, etc;acyloxymethyl groups, e.g. pivaloyloxymethyl, α-acetoxymethyl, etc;ethoxycarbonyl-1-methyl; or α-acyloxy-α-substituted methyl groups, e.g.α-acetoxy-α-methyl-methyl.

When R₃ is "C₂ to C₄ acyloxymethyl" we mean organic moieties such asacetoxymethyl, propionyloxymethyl and butyryloxymethyl.

Examples of the methyl carbamate group of R₃ include carbamoylmethyl,N-methylcarbamoylmethyl, N-butylcarbamoylmethyl,N-propylcarbamoylmethyl, N-(iso-propyl)carbamoylmethyl,N-butylcarbamoylmethyl, N-(sec-butyl)carbamoylmethyl andN-(tert-butylcarbamoylmethyl).

When, in the Formula I, R₃ is a pyridinium group, the terms representedby "T" are exemplified as follows:

the term "C₁ to C₄ alkoxycarbonyl" refers to the methyl, ethyl, propyl,iso-propyl, butyl, sec-butyl and tert-butyl esters of a carboxylic acid,which acid is in turn bound to a pyridinium ring. Analogously, the term"C₁ to C₄ alkanoyl" refers to the formyl, acetyl, propionyl,iso-propionyl, butyryl, sec-butyryl and the tert-butyryl groups, whichare bound through the carbonyl group to a pyridinium ring. Finally, bythe term "C₁ to C₄ alkanoyloxy" refers to the formyloxy, acetyloxy,propionyloxy iso-propionyloxy, butyryloxy, sec-butyryloxy andtert-butyryloxy groups that are bound through the sp³ hydridized oxygento the pyridinium ring.

By the term "halo" we mean fluoro, chloro, bromo or iodo.

The instant invention embraces compounds where the pyridinium group atR₃ is monosubstituted at ring positions 2 through 6 with any of thesubstituents listed for the methyl pyridinium group in claim 1, providedthat, when T is halo or hydroxy, T is bonded only to the 3-position ofthe pyridinium ring. Examples of pyridinium groups that are in turnbound to a 3'-methylene moiety at R₃ include: pyridinium,4-trifluoromethylpyridinium, 3-trifluoromethypyridinium,2-methylpyridinium, 4-methylpyridinium, 3-ethylpyridinium,4-propylpyridinium, 4-butylpyridinium, 3-methoxypyridinium,4-methoxypyridinium, 2-methoxypyridinium, 4-ethoxypyridinium,3-ethoxypyridinium, 4-iso-propoxypyridinium, 3-sec-butoxypyridinium,4-butoxypyridinium, 3-hydroxypyridinium, 4-cyanopyridinium,3-cyanopyridinium, 3-chloropyridinium, 3-iodopyridinium,4-(hydroxymethyl)pyridinium, 3-(hydroxymethyl)pyridinium,4-carboxypyridinium, 4-carbomethoxypyridinium, 3-carbomethoxypyridinium,2-carbomethoxypyridinium, 4-carboethoxypyridinium,3-carbopropoxypyridinium, 4-carbobutoxypyridinium, 4-formylpyridinium,2-formylpyridinium, 3-formylpyridinium, 4-acetylpyridinium,3-acetylpyridinium, 4-propionylpyridinium, 4-tert-butyrylpyridinium,3-butyrylpyridinium, 3-formyloxypyridinium, and3-iso-propionyloxypyridinium.

It should be noted that the amido substituent of the methyl pyridiniumgroup, represented by the formula ##STR21## may be substituted,monosubstituted or disubstituted, as defined, and, in the disubstitutedembodiments, the N-substituents may be the same or different.

Examples of amido-substituted methyl pyridinium ring include N-methylpyridinium-4-carboxamide, pyridinium-3-carboxamide,pyridinium-4-carboxamide, N-cyclopropyl pyridinium-3-carboxamide,N-methyl-N-ethyl pyridinium-3-carboxamide,N,N-dimethylpyridinium-3-carboxamide, N-ethyl pyridinium-4-carboxamideand the like.

Examples of a methyl pyridinium group substituted with a group of theformula ##STR22## include N-(hydroxymethyl)pyridinium-3-carboxamido,N-(hydroxymethyl)pyridinium-4-carboxamido,N-(hydroxyethyl)pyridinium-3-carboxamido,N-(hydroxypropyl)pyridinium-4-carboxamido,N-(hydroxybutyl)pyridinium-3-carboxamido and the like. The preferredamido substituted pyridiniums are theN-(hydroxymethyl)pyridinium-3-carboxamido and theN-(hydroxymethyl)pyridinium-4-carboxamido.

Examples of heterocyclic groups Y when, in Formula I, R₃ is aheterocyclic thiomethyl group --CH₂ --S--Y are 1H-tetrazol-5-yl,1-methyl-1H-tetrazol-5-yl, 1-(n-propyl)-1H-tetrazol-5-yl,1-(sec-butyl)-1H-tetrazol-5-yl, 1-(2-acetic acid)-1H-tetrazol-5-yl,1-(methylsulfonic acid)-1H-tetrazol-5-yl, 5-amino-1,3,4-thiadiazol-2-yl,5-phenyl-1,3,4-thiadiazol-2-yl, 5-methyl-1,3,4-thiadiazol-2-yl,5-ethyl-1,3,4-thiadiazol-2-yl, 5-(n-butyl)-1,3,4-thiadiazol-2-yl,1,3,4-oxadiazol-2-yl, 5-phenyl-1,3,4-oxadiazol-2-yl,5-amino-1,3,4-oxadiazol-2-yl, 5-methyl-1,3,4-oxadiazol-2-yl,5-(iso-propyl)-1,3,4-oxadiazol-2-yl,5-(tert-butyl)-1,3,4-oxadiazol-2-yl, 1,2,4-thiadiazol-2-yl,3-methyl-1,2,4-thiadiazol-5-yl, 3-ethyl-1,2,4-thiadiazol-5-yl,3-(n-butyl)-1,2,4-thiadiazol-5-yl, isothiazol-5-yl,3-methylisothiazol-5-yl, 4-methylisothiazol-5-yl,3-ethyl-isothiazol-5-yl, 4-(n-propyl)-isothiazol-5-yl,3-(iso-propyl)-isothiazol-5-yl, 4 -(n-butyl)-isothiazol-5-yl,3-(sec-butyl)-isothiazol-5-yl, isoxazol-5-yl, 3-methyl-isoxazol-5-yl,4-methylisoxazol-5-yl, 3-ethyl-isoxazol-5-yl, 4-ethyl-isoxazol-5-yl,3-(n-propyl)-isoxazol-5-yl, 4-(iso-propyl)-isoxazol-5-yl,4-(n-butyl)-isoxazol-5-yl, 3-(sec-butyl)-isoxazol-5-yl,1H-1,2,3-triazol-5-yl, 1-methyl-1H-1,2,3-triazol-5-yl,4-methyl-1H-1,2,3-triazol-5-yl, 1,4-dimethyl-1H-1,2,3-triazol-5-yl,1-ethyl-1H-1,2,3-triazol-5-yl, 4-ethyl-1H-1,2,3-triazol-5-yl,1,4-diethyl-1H-1,2,3-triazol-5-yl, 1-(n-propyl)-1H-1,2,3-triazol-5-yl,4-(iso-propyl)-1H-1,2,3-triazol-5-yl,1,4-(di-n-butyl)-1H-1,2,3-triazol-5-yl,1-(sec-butyl)-1H-1,2,3-triazol-5-yl, 1,2,5-thiadiazol-3-yl,1,3,4-triazol-5-yl, 1-methyl-1,3,4-triazol-5-yl,1-ethyl-1,3,4-triazol-5-yl, 1-(n-butyl)-1,3,4-triazol-5-yl,2-methyl-1,3,4-triazol-5-yl, 2-ethyl-1,3,4-triazol-5-yl,2-propyl-1,3,4-triazol-5-yl, 1,2-dimethyl-1,3,4-triazol-5-yl,1,2-(di-n-butyl)-1,3,4-triazol-5-yl,1-methyl-2-ethyl-1,3,4-triazol-5-yl,1-ethyl-2-methyl-1,3,4-triazol-5-yl, 1-propyl-2-methyl-1,3,4-triazol-5-yl, 1,2,3-thiadiazol-5-yl, 4-methyl-1,3,4-thiadiazol-5-yl,4-ethyl-1,2,3-thiadiazol-5-yl, 4-propyl-1,2,3-thiadiazol-5-yl,4-butyl-1,2,3-thiadiazol-5-yl, pyridin-6-yl, 2-methylpyridin-6-yl,3-methylpyridin-6-yl, 4-methylpyridin-6-yl, 5-methylpyridin-6-yl,2-ethylpyridin-6-yl, 4-ethylpyridin-6-yl, 3-ethylpyridin-6-yl,2-(n-propyl)pyridin-6-yl, 3-(n-propyl)pyridin-6-yl,4-(iso-propyl)-pyridin-6-yl, 2-(n-butyl)pyridin-6-yl,4-(sec-butyl)pyridin-6-yl, pyridin-6-yl-N-oxide,1,6,4,5-tetrahydro-5,6-dioxo-4-methyl-as-triazin-3-yl,1,6,4,5-tetrahydro-5,6-dioxo-as-triazin-3-yl,1,6,4,5-tetrahydro-5,6-dioxo-4-ethyl-as-triazin-3-yl,1,6,4,5-tetrahydro-5,6-dioxo-4-(n-propyl)-as-triazin-3-yl,1,6,4,5-tetrahydro-5,6-dioxo-4-(n-butyl)-as-triazin-3-yl,1,6,4,5-tetrahydro-5,6-dioxo-1-methyl-as-triazin-3-yl,1,6,4,5-tetrahydro-5,6-dioxo-1-ethyl-as-triazin-3-yl,1,6,4,5-tetrahydro-5,6-dioxo-1-(iso-propyl)-as-triazin-3-yl,1,6,4,5-tetrahydro-5,6-dioxo-1-(n-butyl)-as-triazin-3-yl,2,5-dihydro-5-oxo-6-hydroxy-as-triazin-3-yl,2,5-dihydro-5-oxo-6-hydroxy-2-methyl-as-triazin-3-yl,2,5-dihydro-5-oxo-6-hydroxy-2-ethyl-as-triazin-3-yl,2,5-dihydro-5-oxo-6-hydroxy-(2-n-propyl)-as-triazin-3-yl,2,5-dihydro-5-oxo-6-hydroxy-(2-n-butyl)-as-triazin-3-yl, pyrazin-2-yl,3-methyl-2-(N-oxide)-pyridizin-6-yl, and like heterocycles.

Preferred heterocycles are 1-methyl-1H-tetrazol-5-yl,5-methyl-1,3,4-thiadiazol-2-yl,2,5-dihydro-5-oxo-6-hydroxy-2-methyl-as-triazin-3-yl and1,6,4,5-tetrahydro-5,6-dioxo-4-methyl-as-triazin-3-yl.

Finally, a proviso in the description of the above cephalosporin is thatwhen R₃ is hydroxy, R₂ can be anything defined except hydrogen.

The intermediate oxide side compound of this invention has the followinggeneral formula ##STR23## wherein R₁ has the same meaning as defined forFormula I; G is chloro, bromo, hydroxy, C₁ to C₄ alkoxy, phenoxy or agroup of the formula

    --O--J

wherein J is the residue of a group forming an activated ester; or agroup of the formula

    --O.sup.⊖ M.sup.⊕

wherein M.sup.⊕ is a monovalent cation; and R₈ is hydrogen or an aminoprotecting group.

The term "active ester" used in the above Formula II refers to the estergroup ##STR24## where J is p-nitrophenol, 2,4-dinitrophenyl,pentachlorophenyl, molecules of the formula ##STR25## and the like. Theterm also includes acid anhydrides and mixed acid anhydrides (ie., where##STR26## and Z is a substituent bound to the carbonyl through a carbonor an oxygen).

The mixed acid anhydride is exemplified by the mixed anhydrides withcarbonic acid monoesters such as monomethyl carbonate, monoisobutylcarbonate, etc. and the mixed anhydrides with lower alkanoic acids whichmay optionally be substituted by halogen, such as pivalic acid,trichloroacetic acid, etc. The preferred active ester groups thefollowing benzotriazole groups that is, where J is ##STR27##

The most preferred of the active ester groups is the former of the abovetwo more preferred benzotriazole groups.

By the term "monovalent cation" we mean cations such as the lithium,sodium and potassium cations, and the like, and the ammonium cationssuch as ammonium, dibenzylammonium, benzylammonium,phenylethylbenzylammonium, 2-hydroxyethylammonium, and the like.

In the above Formula II, when R₈ is an "amino protecting group", I meanexamples such as aromatic acyl groups, e.g. phthaloyl, benzoyl, benzoylgroup substituted with halogen, nitro or lower alkyls of 1 to 4 carbonatoms (e.g. chlorobenzyl, p-nitrobenzyl, p-tert-butylbenzoyl, toluoyl,etc.), naphthyl, phenylacetyl, phenoxyacetyl, benzenesulfonyl andbenzenesulfonyl group substituted with lower alkyls of 1 to 4 carbonatoms (e.g. p-tert-butylbenzenesulfonyl, toluenesulfonyl, etc.),camphorsulfonyl, methanesulfonyl, acyl groups derived from aliphatic orhalogenated aliphatic carboxylic acids such as acetyl, valeryl,n-decanoyl, acryloyl, pivaloyl, halogenoacetyl (e.g. monochloroacetyl,monobromoacetyl, dichloroacetyl, trichloroacetyl, etc.); esterifiedcarboxyls such as ethoxycarbonyl, tert-butyloxycarbonyl,isobornyloxycarbonyl, phenyloxycarbonyl, trichloroethoxycarbonyl,benzyloxycarbonyl, carbamoyl groups such as methylcarbamoyl,phenylcarbamoyl, naphthylcarbamoyl, etc., the correspondingthiocarbamoyl groups. N-mono-, di- and trihalogenoacetylcarbamoyloxygroups such as N-chloroacetylcarbamoyloxy, N-chlorosulfonylcarbamoyloxy,N-trimethylsilylcarbamoyloxy, etc., the phenylglycyloxy group, and di-and trialkyl silyl protecting groups such as the trimethylsilyl group.The nature of the amino protecting group is not critical so long as theprotected amino group survives the reaction condition while carrying outa reaction on another part of the molecule, and that subsequently theprotecting group can be removed without disrupting the structure of therest of the molecule.

The preferred amino protecting group is 2-chloroacetyl.

It should be noted that R₈ need only be an amino protecting group whenthe methoxy ester is being cleaved during the synthesis of the compoundof Formula II, and need not be protected when the compound of FormulaIII is acylated with the compound of Formula II, as discussed below.

The preferred method of synthesis for the compounds of Formula I of theinstant application involves acylating a compound of the Formula III##STR28## with the intermediate oxime side chain of Formula IV ##STR29##wherein R₁, R₂, R₃ and G have the same meanings as described before.

In this preferred method of synthesis the desired R₃ group is in placebefore the acylation reaction is carried out.

The preferred variation for carrying out the above acylation reactionoccurs when G is a group of the formula

    --O--J

wherein J is the residue of a group forming an activated ester.Preferred groups at J are ##STR30## with the latter two groups (the1-N-oxide benzotriazole and isobutyloxycarbonyl) being more preferred,and the 1-N-oxide benzotriazole moiety being most preferred.

Alternatively, when G in Formula IV is hydroxy or the salt form thereof,the oxime side chain is coupled with the 7-amino nucleus (Formula III)via N-acylation employing a suitable condensing agent. The condensingagent is exemplified by N,N'-disubstituted carbodiimides such asN,N'-dicyclohexylcarbodiimide, N,N'-diethylcarbodiimide,N,N'-di-n-propylcarbodiimide, N,N'-diisopropycarbodiimide,N,N'-diallylcarbodiimide, N,N'-bis(p-dimethylaminophenyl)carbodiimide,N-ethyl-N'-(4"-ethylmorpholinyl)carbodiimide and the like, othersuitable carbodiimides being disclosed by Sheehan in U.S. Pat. No.2,938,892 and by Hofmann et al. U.S. Pat. No. 3,065,224; azolides suchas N,N'-carbonylimidazole, N,N'-thionyldiimidazol, etc.; dehydratingagents such as N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline,phosphorus oxychloride, alkoxyacetylene, etc., and 2-halogenopyridiniumsalts (such as 2-chloropyridinium methyl iodide, 2-fluoropyridiniummethyl iodide, etc.). Specific examples of the above acylation reactioncan be found in the Experimental section.

In addition, the above preferred method of synthesis for thecephalosporin compound in Formula I can also be carried out when G ischloro or bromo.

When G is C₁ to C₄ alkoxy or phenoxy in the above Formula IV, theseesters can be converted to the active esters, the carboxylic acid orcarboxylate salt or the acyl chloride or bromide by methods well knownin the art to facilitate acylation the cephalosporin nucleus,represented by Formula III above.

An alternative synthesis for the compounds of Formula I, wherein R₃ is amethyl pyridinium group of the formula ##STR31## or a heterocyclicthiomethyl group of the formula

    --CH.sub.2 --S--Y

(where T and Y are as described for Formula I), entails the reaction ofa 3-halomethylcephalosporin, represented by the Formula V ##STR32##wherein R₁ and R₂ are as defined above for Formula I and X is chloro,bromo or iodo, with a pyridine moiety of the formula ##STR33## or aheterocyclic mercaptide moiety, (derived from the above heterocyclicthiol moieties of the formula H--S--Y), of the formula

    M.sup.⊕⊖ S--Y

Preferably, X is iodo and R₂ is a trialkyl silyl group such as tri(C₁ toC₄ alkyl)silyl ester, for example, trimethylsilyl or triethylsilyl.

It is also desirable that nucleophilic substituents on the pyridine andon the heterocyclic mercaptide moieties, such as carboxy, hydroxy andsulfonic acid functions, be suitably protected so that thesesubstituents do not interfere with the displacement reaction by thenitrogen of the pyridine or the sulfur of the heterocyclic mercaptide.These protecting groups can be removed once the displacement reaction iscarried out.

The 3-halomethyl substituted compounds can be prepared by methods knownin the art, for example, by the acylation of a3-halomethyl-7-amino-3-cephem nucleus compound. The preferred3-iodomethyl compounds of the Formula 2 are best obtained by the methoddescribed by R. Bonjouklian, U.S. Pat. No. 4,266,049. According to thismethod, a 7-acylamido-3-acetoxymethyl-3-cephem-4-carboxylic acid isfirst silylated to block reactive groups such as the C₄ carboxylic acidgroup and the silylated derivative is reacted with atrialkylsilyliodide, e.g. trimethylsilyliodide (TMSI), to form the3-iodomethyl silylated derivative. The latter is then reacted with theabove pyridine or the above heterocyclic mercaptide and the silyl blocksare hydrolyzed to provide a compound of the Formula I. The preparationof compounds of the Formula 1 by this method is illustrated by thefollowing general reaction Scheme I: ##STR34##

In the above Scheme, when ##STR35## W is a negative charge, and whenQ=S--Y, W is hydrogen.

The reaction is carried out with either the pyridine or the heterocyclicthiol at a temperature between about 20° C. and about 45° C. in an inertaprotic organic solvent under substantially anhydrous conditions. Thereaction in either case is conveniently carried out at ambienttemperature or at slightly elevated temperatures. Solvents which can beused with the pyridines and the thiols are, for example, acetonitrile,propionitrile, dimethylformamide, dimethylacetamide and like commonlyused aprotic solvents.

Alternatively, the compounds of Formula I, wherein R₃ is a methylpyridinium substituent of the formula ##STR36## or a heterocyclicthiomethyl group of the formula

    --CH.sub.2 --S--Y

can be prepared by the well-known displacement reaction using a3-acetoxymethyl-3-cephem-4-carboxylic acid as a substrate. The acetoxygroup is displaced by a pyridine or a heterocyclic mercaptide compound(derived from the above heterocyclic thiol moiety), as illustrated inthe following Scheme II: ##STR37##

In Scheme II, R, W, Q, T and Y mean the same as they did for Scheme I.

The preparation of the 3-heterocyclicthiomethyl substituted compounds(Formula I, R₃ is CH--S--Y) by the displacement reaction in Scheme II isbest carried out by the method of Hatfield, U.S. Pat. No. 4,144,391,issued Mar. 13, 1979. According to this method the displacement reactionis carried out under anhydrous conditions.

The preparation of 3-methyl pyridinium compounds according to the methoddescribed by Scheme II is carried out in an aqueous solvent systemcomprising a water miscible solvent such as acetone or acetonitrile. Ingeneral the reaction proceeds at a temperature between about 25° C. andabout 65° C.

As with Scheme I, in Scheme II, it is again desirable that thenucleophilic substituents on the pyridine and on the heterocyclicmercaptide, such as carboxy, hydroxy and sulfonic acid functions, besuitably protected so as not to interfere with the displacementreactions of the nitrogen of the pyridine or the sulfur of theheterocyclic mercaptide. These protecting groups can be removed afterthe displacement reaction is carried out.

The synthesis of the intermedate oxime side chain compound of Formula IIis an adaptation of a synthesis found in various literature references.

The general method of synthesis for the oxime side chains of the instantapplication is outlined by the specific synthesis of the following oximeside chain, depicted in Scheme III: ##STR38##

In the above Scheme III, compound 1(ethyl-γ-bromo-α-methoximinoacetoacetate) was reacted with urea and zincoxide in acetone or methylethylketone to give cyclized compound 2(2-(2-amino-oxazol-4-yl)-2-Z-methoximinoacetate). Compound 2 in turn isreacted with chloroacetyl chloride in the presence of triethylamine inaqueous dimethylacetamide to give the amino-protected derivativecompound 3 (ethyl2-[2-(2-chloroacetamido)oxazol-4-yl]-2-Z-methoximinoacetate). Compound 3is then saponified to the sodium carboxylate salt with aqueous sodiumhydroxide solution and converted to the free carboxylic acid uponacidification with a suitable acid, e.g. hydrochloric acid.

The preparation of the oxime side chain (Formula II) wherein R₁ is acarboxy-substituted alkyl or carboxy-substituted cycloalkyl group of theformula ##STR39## (wherein a, b, m and R' mean the same as for Formula Iabove) is accomplished by alkylation of the oxime group of the oximeside chain precursor represented by Formula VI, ##STR40## (wherein R₉ isa carboxy-protecting group and R₈ is an amino-protecting group), and agroup of the Formula VII ##STR41## (wherein a, b and R' is as describedfor the compound of Formula I and Z is chloro, bromo, iodo, sulfate orsulfonate such as tosylate), followed by removal of thecarboxy-protecting R₉ and the amino-protecting group R₈. The alkylationreaction is generally carried out in the presence of a base, e.g.potassium carbonate or sodium hydride, and is preferably conducted in anorganic solvent, for example, dimethylsulfoxide, a cyclic ether such astetrahydrofuran or dioxan, or an N,N-disubstituted amide such asdimethylformamide.

The preferred cephalosporin compounds of Formula I include:

benzhydryl7β-[2-[2-(aminooxazol)-4-yl]-2-Z-methoximinoacetamido]-3-acetoxymethyl-3-cephem-4-carboxylate,

7β-[2-[(2-aminooxazol)-4-yl]-B2-Z-methoximinoacetamido]-3-acetoxymethyl-3-cephem-4-carboxylic acid,

7β-[2-[ (2-aminooxazol)-4-yl]-2-Z-methoxyiminoacetamido]-3-methylpyridinium-3-cephem-4-carboxylate,

Benzhydryl7β-[2-[(2-aminooxazol)-4-yl]-2-Z-methoximinoacetamido]-3-cephem-4-carboxylate,

7β-[2-[(2-aminooxazol)-4-yl]-2-Z-methoximinoacetamido]-3-cephem-4-carboxylate,

Benzhydryl7β-[2-[(2-aminooxazol)-4-yl]-2-Z-methoximinoacetamido]-3-(2,5-dihydro-2-methyl-5-oxo-6-hydroxy-as-triazin-3-thiomethyl)-3-cephem-4-carboxylate,and

7β-[2-[(2-aminooxazol)-4-yl]-2-Z-methoximinoacetamido]-3-(2,5-dihydro-2-methyl-5-oxo-6-hydroxy-as-triazin-3-thiomethyl)-3-cephem-4-carboxylicacid.

More preferred cephalosporin compounds include:

benzhydryl7β-[2-[(2-aminooxazol)-4-yl]-2-Z-methoximinoacetamido]-3-acetoxymethyl-3-cephem-4-carboxylate,

7β-[2-[(2-aminooxazol)-4-yl]-2-Z-methoximinoacetamido]-3-acetoxymethyl-3-cephem-4-carboxylicacid, and

7β-[2-[(2-aminooxazol)-4-yl]-2-Z-methoximinoacetamido]-3-methylpyridinium-3-cephem-4-carboxylate.

The cephalosporin compounds claimed in the instant application(represented by Formula I above), either as free carboxylic acids,non-toxic pharmaceutically acceptable salt, of the carboxylic acid thehydrates of said salt, the non-toxic metabolically labile esters, withor without the acid addition form at the 2-amino position of theoxazolyl ring, are useful for treating infections in warm-bloodedanimals caused by gram-positive and by gram-negative bacteria. Thecompounds can be administered parenterally using pharmaceuticallyacceptable formulations.

The antibiotic compounds of the formula (wherein R₂ is H, or ametabolically labile ester), or the pharmaceutically acceptable,non-toxic salts thereof can be administered in an effective dose ofbetween about 50 mg to about 2.5 g in the treatment and control ofinfectious diseases. The particular dosage regime may vary depending onsuch factors as the nature of the infection; the severity of thedisease, the general health and age of the patient as well as thetolerance of the individual patient to the antibiotic. For example, theantibiotic may be administered two or more times per day and suchtreatment may extend for several days to two weeks or longer ifnecessary. The compounds can be administered intramuscularly orintravenously. For the i.v. route the compounds can be administered bythe drip method whereby a pharmaceutical formulation comprising theantibiotic and a physiologically acceptable diluent is infused.Pharmaceutically acceptable diluents include, for example, 5% dextrose,0.9% saline, Ringer's solution or other suitable diluents.

These compounds can also be administered as veterinary compositions,such as, for example, in the feed or drinking water of farm animals totreat infections such as colibacillosis or swine dysentery.

Alternatively, these compounds can be used as surface disinfectants.Solutions containing as little as 0.1 percent by weight of theantibiotic are effective for disinfecting purposes. Such solutions,preferably also containing a detergent or other cleansing agent, areuseful for disinfecting objects such as glassware, dental and surgicalinstruments, and surfaces such as walls, floors, and tables in areaswhere maintenance of sterile conditions is important, i.e. hospitals,food-preparation areas, and the like.

The antibacterial activity of the compounds of this invention isillustrated by the following in vitro and in vivo test data obtainedwith representative compounds. In Table I, the minimum inhibitoryconcentration (MIC) for a representative compound against a wide rangeof gram-positive and gram-negative bacteria is presented. The MIC valueswere obtained by the standard agar dilution test.

                                      TABLE 1                                     __________________________________________________________________________    Antibiotic Activity of 7β-[2-(2-Aminooxazol-4-yl)-2-                     (Z-Methoximino)acetamido-3-Acetoxymethyl-3-Cephem-4-                          Carboxylic Acid vs. Gram-Positive and Gram-Negative Bacteria                  __________________________________________________________________________    Test Organism*                                                                          a b c  d e f g  h  i   j k  l  m  n o  p  q                         __________________________________________________________________________    Minimum Inhibitory                                                                      2 4 128                                                                              16                                                                              4 64                                                                              0.03                                                                             0.015                                                                            >128                                                                              32                                                                              0.125                                                                            0.125                                                                            0.25                                                                             0.5                                                                             0.125                                                                            0.06                                                                             0.03                      Concentration                                                                 (mcg/ml)                                                                      __________________________________________________________________________    Test Organism*                                                                          r s  t u v w   x  y z  a'                                                                              b' c'                                                                              d'                                                                              e'                                                                              f' g'  h'                                                                              i'                       __________________________________________________________________________    Minimum Inhibitory                                                                      64                                                                              0.125                                                                            0.5                                                                             0.5                                                                             1 >128                                                                              0.25                                                                             0.5                                                                             128                                                                              64                                                                              128                                                                              8 16                                                                              2 0.125                                                                            0.015                                                                             0.5                                                                             8                        Concentration                                                                 (mcg/ml)                                                                      __________________________________________________________________________     a Staphylococcus aureus X1.1                                                  b Staphylococcus aureus V41                                                   c Staphylococcus aureus X400                                                  d Staphylococcus aureus S13E                                                  e Staphylococcus epidermidis EPI1                                             f Staphylococcus epidermidis EPI2                                             g Streptococcus pyogenes  C203                                                h Streptococcus pneumoniae Park                                               i Streptococcus group D X66                                                   j Streptococcus group D 9960                                                  k Hemophilus influenzae C.L.                                                  l Hemophilus influenzae 76                                                    m Shigella sonnei N9                                                          n Escherichia coli N10                                                        o Escherichia coli EC14                                                       p Escherichia coli TEM                                                        q Klebsiella pneumoniae X26                                                   r Klebsiella pneumoniae KAE                                                   s Enterobacter aerogenes X68                                                  t Enterobacter aerogenes C32                                                  u Enterobactor aerogenes EB17                                                 v Enterobacter cloacae EB5                                                    w Enterobacter cloacae 265A                                                   x Salmonella heidelberg X514                                                  y Salmonella typhimurium 1335                                                 z Pseudomonas aeruginosa X528                                                 a' Pseudomonas aeruginosa X239                                                b' Pseudomonas aeruginosa Ps18                                                c' Serratia marcescens X99                                                    d' Serratia marcescens SE3                                                    e' Proteus morganii PR15                                                      f' Proteus inconstans PR33                                                    g' Proteus rettgeri PR7                                                       h' Proteus rettgeri C24                                                       i' Citrobacter freundii CF17                                             

EXPERIMENTAL SECTION

In the following experimental procedure, the references to "dry columnsilica gel column chromatography" embodies the following generalprocedure:

Dry column silica gel (I.C.N. Nutritional Biochemicals) is poured into acolumn fitted with a fritted Buchner funnel and stopcocks at one end. Anadditional amount of this dry column silica gel, to which the compoundto be chromatographed has been absorbed, is added to the top of thecolumn. A paper filter disc is placed at the top of the column and thedesired eluting solvent mixture is started through the column. Theeluant was collected in 25 ml. fractions. The progress of the seperationis followed by thin layer chromatography and the fractions are combinedwhen appropriate.

The abbreviations THF, v:v, and h. stand for tetrahydrofuran, volume tovolume, and hours, respectively.

The abbreviations m.p., u.v., i.r., n.m.r. and m.s. stand for meltingpoint, ultraviolet spectra, infrared spectra, nuclear magnetic resonancespectra and mass spectra, respectively. In addition, the absorptionmaxima listed for the i.r. spectra are only those of interest and notall of the maxima observed.

In conjunction with the n.m.r. spectra, the following abbreviations areused: "s" is singlet, "d" is doublet, "dd" is doublet of doublets, "br.s" is broad singlet, "t" is triplet, "q" is quartet, "m" is multiplet."J" indicates the coupling constant in Hertz. "DMSO/d₆ " is dimethylsulfoxide where all protons have been replaced with deuterium.

The n.m.r. spectra were obtained on a Varian associates EM-390 90 MHz ora Jeol FT 90Q instrument. The chemical shifts are expressed in δ values(parts per million downfield from tetramethylsilane).

EXAMPLE 1

Preparation of 2-[(2-aminooxazol-4-yl]-2-Z-methoximinoacetic acid

Step A

Preparation of ethyl 2-[2-aminooxazol-4-yl]-2-methoximinoacetate

Method 1

Zinc oxide (0.406 g, 5 mmol) was suspended in a mixture composed of urea(3 g, 50 mmol) and ethyl-γ-bromo-α-methoximinoacetate (2.52 g, 10 mmol)in acetone (100 ml), and this mixture was filtered through super-cel,then was concentrated, dissolved in ethyl acetate, and the ethyl acetatesolution was washed with 5% aqueous sodium bicarbonate solution andwater (2×). The solution was then dried over magnesium sulfate,filtered, and concentrated in vacuo. The unreacted bromoketone wasremoved by trituration with ether and hexane. The residue wascrystallized from 2B-ethanol to yield 0.015 g of ethyl2-[2-aminooxazol-4-yl]-2-Z-methoximinoacetate; melting point 138°-140°C., and this compound had an n.m.r. spectrum similar to the spectrum forthe product in Method 3, infra. The mother liquors from the ethanolcrystallization were used as described in Method 3, infra.

Method 2

Zinc oxide (0.812 g, 10 mmol) was suspended in a mixture composed ofurea (3 g, 50 mmol) and ethyl-γ-bromo-α-methoximinoacetoacetate (2.52 g,10 mmol) in acetone (100 ml) and stirred under reflux for 85 hours. Thereaction mixture was allowed to cool to room temperature, was filtered,and the filtrate was concentrated in vacuo. The residue was partitionedbetween ethyl acetate and 5% aqueous sodium bicarbonate solution. Afterwashing the solution with water (2×), the ethyl acetate solution wasextracted with 1 N hydrochloric acid. The acidic aqueous layer waswashed with fresh ethyl acetate, then layered with ethyl acetate andmade basic by the addition of aqueous sodium bicarbonate solution. Thecombined ethyl acetate extracts were dried over magnesium sulfate,filtered and evaporated. The residue was crystallized from (2B ethanol)yielding 0.010 g of the same product as isolated in Method 1. The motherliquors from the ethanol crystallization were used as described inMethod 3, infra.

Method 3

The reaction was run as in Method 1, using 25.2 g (100 mmol) ofethyl-γ-bromo-α-methoximinoacetoacetate, 30 g (500 mmol) of urea, 4.06 g(50 mmol) of zinc oxide and substituting methylethylketone (1000 ml) foracetone. The product obtained from the 2B-ethanol crystallization wasrecrystallized from isopropanol to yield approximately 800 mg of theproduct, ethyl-2-[2-aminooxazol-4-yl]-2-methoximinoacetate. Thismaterial was combined with the crystalline lots from Methods 1 and 2,recrystallized from isopropanol to give 0.671 g of the desired product.

The mother liquors from the crystallization (ethanol) andrecrystallization (isopropanol) were combined with the mother liquors ofthe crystallizations of Methods 1 and 2, evaporated, and the residue waschromatographed over dry column alumina, using ethyl acetate as theeluant. The fractions containing predominantly the desired product wererecombined and rechromatographed as above, and the fractions containingpure product were recrystallized from isopropyl alcohol, to yield 0.1 gof ethyl 2-[2-amino-4-yl]-2-Z-methoximinoacetate; n.m.r. (CDCl₃) δ1.4(t, 3, CH₃ CH₂), 4.0 (s, 3, CH₃ O), 4.4 (q, 2, CH₃ CH₂ --), 5.67 (br, s,2, amino), 7.3 (s, 1, oxazole aromatic); i.r. (KBr) 1870 cm⁻¹ ; u.v.(methanol) λ_(m) =217 nm (ε_(m) =18,873), λ_(m) =275 nm (ε_(m) =3370);m.s. M⁺ =213; Analysis: Calculated for: C₈ H₁₁ N₃ O.sub. 4 : C, 45.07;H, 5.20; N, 19.71. Found: C, 45.05; H, 5.37; N, 19.40.

Method 4

Ethyl γ-bromo-α-methoximinoacetoacetate (100 g, 0.397 mmol), urea (91 g,1.98 mmol), and zinc oxide (16 g, 0.198 mmol) were dissolved inmethylethylketone (3 l) and the solution was stirred under reflux for 48hours then allowed to cool. The solution was filtered and concentratedin vacuo. The dark residue was dissolved in ethyl acetate and filtered.The filtrate was evaporated in vacuo and the residue was chromatographedover activity III neutral alumina. The column was eluted sequentiallywith neat cyclohexane (1000 ml), 1:9 v:v ethyl acetate:cyclohexane (1000ml), 2:8 v:v ethyl acetate:cyclohexane (2000 ml), 3:7 v:v ethylacetate:cyclohexane (500 ml), and finally with 1:1 v:v ethylacetate:cyclohexane until no more product was eluted. Fifty-fivefractions were taken, although fractions 51 through 55 were 500 ml orgreater. The crude product was contained in fractions 51, 52, and 53.The three fractions were evaporated to give a semi-crystalline mass,each of which were triturated with ether and filtered to yield 3 purecrops of crystals of product. These crops of crystals were combined witha second crop of crystals obtained from fraction B 52 to yield 8.9 g ofethyl 2-[2-aminooxazol-4-yl]-2-Z-methoximinoacetate, which gave ann.m.r. spectrum similar to the spectrum obtained for the product inMethod 3.

Step B

Preparation of ethyl2-[2-(2-chloroacetamido)-oxazol-4-yl]-2-Z-methoximinoacetate

Method 1

A mixture of ethyl 2-[2-aminooxazol-4-yl]-2-Z-methoximinoacetate (2.13g, 10 mmol), triethylamine (1.53 ml, 11 mmol) and aqueousdimethylacetamide solution (25 ml) were chilled to 0° C. with an icebath. A dimethylacetamide solution (10 ml) of chloroacetyl chloride(0.939 ml, 11 mmol) was added dropwise to the stirred solution. Thereaction mixture was stirred for 0.5 hour at 0° C., followed by stirringat 19 hours at room temperature. The reaction mixture was poured ontoice and the resultant mixture was extracted with ethyl acetate. Theethyl acetate was washed with water, dried over anhydrous magnesiumsulfate, filtered and concentrated in vacuo. After evacuating under highvacuum for 24 hours, the residue was triturated with ether and filtered.The mother liquor was evaporated and the residue was recrystallized fromcarbon tetrachloride to give 0.456 g of ethyl2-[2-(2-chloroacetamido)oxazol-4-yl]-2-Z-methoximinoacetate; m.p.;91°-92° C., n.m.r. (CDCl₃) δ1.32 (t, 3, --CH₃, J=7.5 Hz), 4.0 (s, 3,OCH₃), 4.1 (s, 2 Cl--CH₂ --), 4.37 (q, 2, --O--CH₂ --, J= 5.7 Hz), 7.25(s, 1, aromatic proton).

Method 2

A mixture of ethyl 2-[2-aminooxazol-4-yl]-2-Z-methoximinoacetate (3.2 g,18.24 mmol), triethylamine (2.82 ml, 20 mmol) and dimethylacetamide (90%aqueous, 50 ml) were chilled to 0° C. by means of an ice bath. Ananhydrous dimethylacetamide (12 ml) of chloroacetyl chloride (1.83 ml,20 mmol) was added dropwise to the stirred solution. The reactionmixture was stirred for 0.5 hour at 0° C. then for 15 hours at roomtemperature.

The mixture was poured into ice and extracted with ethyl acetate (2×).The ethyl acetate layers were combined and were washed with water (2×),were dried over magnesium sulfate, filtered, concentrated in vacuo, thenwere further dried under high vacuum. The residue was triturated withether and filtered. The filtrate was concentrated and recrystallizedfrom carbon tetrachloride yielding 0.354 g (43%) of ethyl2-[2-(2-chloroacetamido)oxazol-4-yl]-2-Z-methoximinoacetate. Thiscompound had the same n.m.r. spectrum as the spectrum of the compound ofMethod 1, above.

Step C

Preparation of 2-[(2-aminooxazol)-4-yl]-2-Z-methoximinoacetic acid

Method 1

Sodium hydroxide (5 N, 2 equivalents plus a 10% excess, 4.6 ml, 22.86mmol) was added dropwise to a stirred suspension of ethyl2-[2-(chloroacetamido)-oxazol-4-yl]-2-Z-methoximinoacetate (3.0 g, 10.38mmol) in water (90 ml). Dissolution of the ester was complete withinabout 15 to 20 minutes, and the stirring was continued for an additionalhour. The mixture was chilled and acidified by the dropwise addition of1 N hydrochloric aicd (6 ml). The aqueous layer was saturated withsodium chloride and the mixture was saturated with large quantities ofethyl acetate. The ethyl acetate extracts were dried over anhydroussodium sulfate, filtered, combined and concentrated in vacuo, yielding0.453 g of 2-[(2-aminooxazol)-4-yl]-2-Z-methoximinoacetic acid; meltingpoint; 170°-174° C. (decomposed), n.m.r. (DMSO/d₆) δ3.84 (s, 3, NOCH₃),6.77 (br, s, 2, amino), δ7.48 (s, 1, aromatic proton).

Method 2

Ethyl 2-[2-(chloroacetamido)oxazol-4-yl]-2-Z-methoximinoacetate (1.74 g,5.95 mmol) was suspended in water and the suspension was chilled in anice bath. Sodium hydroxide (5 N, 2.6 ml, 13.09 mmol) was added andstirring was continued as the material slowly went into solution. After1.5 hours of stirring at 0° C., the solution was allowed to slowly cometo room temperature. This aqueous solution was then treated with XADresin (8 ml, 1.7 mmol/ml) and stirred for 2 minutes. The solution wasfiltered and the resin was washed with water (5 ml) and the aqueousfiltrate was lyophilized to yield 0.812 g of2-(2-aminooxazol-4-yl)-2-Z-methoximinoacetic acid, which had the samen.m.r. spectrum as the spectrum of the product in Method 1.

EXAMPLE 2

Preparation of Benzhydryl7β-[2-[(2-aminooxazol)-4-yl]-2-Z-methoximinoacetamido]-3-acetoxymethyl-3-cephem-4-carboxylate

2-(2-Aminooxazol-4-yl)-2-(Z-methoximino) acetic acid (0.261 g, 1 mmol)was dissolved in a mixture of dimethylacetamide (3 ml) and methylenechloride (3 ml). Triethylamine (0.139 ml, 1 mmol) was added to thissolution, then the resultant mixture was added dropwise to a stirred,chilled methylene chloride (25 ml) of isobutyl-chlorocarbonate. Thisreaction mixture was stirred for 1 hour, at the end of which time amethylene chloride (5 ml) solution of benzhydryl7β-amino-3-acetoxymethyl-3-cephem-4-carboxylate was added dropwise.Initially, the resultant reaction mixture was stirred at 0° to 10° C.but was allowed to gradually warm to ambient temperature and stirringwas continued overnight.

The solvent from the reaction mixture was removed in vacuo and theresidue was taken up in ethyl acetate. The ethyl acetate solution waswashed sequentially with 1 N hydrochloric acid, 10% aqueous sodiumbicarbonate, and saturated aqueous sodium chloride solution. Removal ofthe ethyl acetate solvent in vacuo, after drying the solution oversodium sulfate and filtering, resulted in a yellow foam. This crudeproduct mixture was chromatographed over Activity III Silica Gel(100-200 mesh, Woehlm). Elution was begun with 7:3 v:v ethylacetate:cyclohexane (fractions 1 through 9), then neat ethyl acetate(fractions 20 through 34), and finally 9:1 v:v ethyl acetate:methanol(fractions 34 through 37). The desired product, benzhydryl7β-[2-[(2-aminooxazol)-4-yl]-2-Z-methoximinoacetamido]-3-acetoxymethyl-3-cephem-4-carboxylate,was contained in fractions 14 through 30, and these fractions combinedto yield 0.100 g of the desired product: n.m.r. (CDCl₃) δ1.98 (s, 3,methyl of 3-acetoxymethyl), 3.3 and 3.56 (ABq, 2, C-2), 4.75 and 5.01(ABq, 2, C-3'), 5.02 (d, 1, C-6), 5.25 (br, s, 2, amino), 5.95 (q, 1,C-7), 7.91 (s, 1, benzhydryl methine proton), 7.3 (m, 11, phenyl ringsand oxazole ring), 8.42 (d, 1, amido proton).

EXAMPLE 3

Preparation of7β-[2-[(2-aminooxazol)-4-yl]-2-Z-methoximinoacetamido]-3-acetoxymethyl-3-cephem-4-carboxylicacid

Benzhydryl7β-[2-[(2-aminooxazol)-4-yl]-2-Z-methoximinoacetamido]-3-acetoxymethyl-3-cephem-4-carboxylate(approximately 100 mg, 0.16 mmol) was dissolved in a mixture of formicacid (97-100%, 4 ml) and triethylsilane (0.04 ml, 0.25 mmol), and thisreaction mixture was stirred at room temperature for 3 hours. Thereaction mixture was diluted with ethyl acetate, evaporated to gum, andthe gum was purged with an ethyl acetate/acetonitrile mixture (2×) togive a light brown powder. This powder was further dried by evaporationin vacuo for 1 hour. The brown powder was then dried with ether for 0.5hour, sonnicated, filtered and air-dried to yield 64 mg (91%) of7β-[2-[(2-aminooxazol)-yl]-2-Z-methoximinoacetamido]-3-acetoxymethyl-3-cephem-4-carboxylicacid; n.m.r. (DMSO/d₆)δ, 3.4 (m, 2, C-2), 3.85 (s, 3, ═NOCH₃), 4.85 (q,2, J= 16, C-3'), 5.15 (d, 1, J=6, C-6), 5.8 (q, 1, J=4, C-7), 6.85 (s,2, amino), 7.5 (s, 1, oxazole ring), 9.6 (d, 1, J=9, amido).

EXAMPLE 4

Preparation of 1-(N-oxide)benzotriazol-3-yl2-[2-aminooxazol-4-yl]-2-Z-methoximinoacetamide

A mixture of 1-hydroxybenzotriazole monohydrate (1.02 g, 6.68 mmol) andtriethylamine (1.14 ml, 8.16 mmol) in dimethylacetamide (8 ml) waschilled in an ice-acetone bath and a dimethylacetamide (2 ml) solutionof methanesulfonyl chloride (0.57 ml, 7.3 mmol) was added dropwise.Stirring of the resultant solution at 0° to 10° C. was continued for 1.5hours.

2-[2-Aminooxazol-4-yl]-2-Z-methoximinoacetic acid (1.235 g, 6.68 mmol),dissolved in dimethylacetamide (2.5 ml), together with triethylamine(1.01 ml) was then added dropwise to the reaction mixture, and thesolution was stirred at 0° to 10° C. for an additional 1.5 hours. Water(21 ml) was then added in a dropwise fashion, resulting in the formationof a precipitate shortly following the addition. Within 10 minutes afterthe water had been added, the precipitate formed, was collected byfiltration, was washed with cold water, and was dried in vacuo to yield1.277 g (63%) of 1-(N-oxide)benzotriazol-3-yl2-[2-aminooxazol-4-yl]-2-Z-methoximinoacetamide: n.m.r. (CDCl₃ plusDMSO/d₆, obtained from the same product of another procedure) δ3.90 (s,3, --OCH₃), 5.95 (br. s, 2, amino), 7.43 (s, 1, oxazole proton),7.45-8.1 (m, 3, the C-5, 6, and 7 protons of the benzotriazole moiety),8.45 (d, 1, the C-4 proton of the benzotriazole moiety).

EXAMPLE 5

Preparation of7β-[2-[2-aminooxazol-4-yl]-2-Z-methoximinoacetamido]-3-acetoxymethyl-3-cephem-4-carboxylicacid

7β-Amino-3-acetoxymethyl-3-cephem-4-carboxylic acid (0.43 g, 1.58 mmol)was suspended in a 1:1 v:v water:acetone solvent (25 ml) andtriethylamine (0.2 ml, 1.48 mmol) was added dropwise to the stirredsolution, which was cooled in an ice bath. After the cephalosporinsubstrate was in solution, 1-(N-oxide)benzotriazol-3-yl2-[2-aminooxazol-4-yl]-2-Z-methoximinoacetamide (0.5 g, 1.66 mmol) wasadded portionwise. The pH of this solution was maintained atapproximately 7.5 by the periodic additions of 45% aqueous potassiumphosphate solution. After the addition of the benzotriazole amide wascomplete, the mixture was slowly allowed to warm to room temperature.After approximately 2 hours, dissolution had occurred and stirring ofthe solution was continued overnight. The acetone was removed, and theaqueous solution was diluted with water, layered with ethyl acetate, andthe pH of the solution was adjusted to pH 2.5 by the addition of 1 Nhydrochloric acid. The ethyl acetate layer was then separated, driedover magnesium sulfate, filtered and evaporated in vacuo. The residuewas partially crystalline, and the residue was then triturated withether and filtered to yield 0.3 g of7β-[2-[2-aminooxazol-4-yl]-2-Z-methoximinoacetamido]-3-acetoxymethyl-3-cephem-4-carboxylicacid: n.m.r. (DMSO/d₆) δ2.0 (s, 3, OAc), 3.32 and 3.61 (ABq, 2, J=18 Hz,C-2 protons), 4.85 (s, 3, OCH₃), 4.7 and 5.0 (ABq, 2, J=12 Hz, C-3'protons), 5.08 (d, 1, J=4.5 Hz, C-6 proton), 5.72 (q, 1, J=4.5 and 9 Hz,C-7 proton), 6.6 (br. s, 2, amino), 7.38 (s, 1, oxazole aromaticproton), 9.5 (d, 1, J=9 Hz, 7-amido N-proton); u.v. (methanol) λmax=217(ε_(m) =19,254), λmax=265 (ε_(m) =10,200);

Analysis: Calculated: C, 43.74; H, 3.90; N, 15.94. Observed: C, 44.01;H, 3.97; N, 15.75.

EXAMPLE 6

Preparation of 1-(N-oxide)benzotriazol-3-yl2-[(2-aminooxazol)-4-yl]-2-Z-methoximinoacetamide

Methanesulfonyl chloride (0.046 ml, 0.059 mmol) was dissolved indimethylacetamide (0.46 ml). This solution was diluted to a total of 1ml with additional dimethylacetamide and an aliquot (0.1 ml) of thisdiluted solution was added dropwise to a cold (0° to 10° C.), stirringdimethylacetamide (0.65 ml) solution of triethylamine (0.092 ml, 0.66mmol) and 1-hydroxybenzotriazole monohydrate (0.08 ml, 27 g, 0.54 mmol).The resultant mixture was stirred for 1.5 hours.2-(Aminooxazol-4-yl)-2-Z-methoximinoacetic acid (0.1 g, 0.54 mmol) wasadded to this mixture followed by the addition of a dimethylacetamide(0.2 ml) solution of triethylamine (0.082 ml) and this mixture wasstirred for 1.5 hours. Water (1.7 ml) was added dropwise causing aprecipitate to form. The precipitate was collected by filtration thenair dried under vacuum to give 0.1 g of 1-[N-oxide]-benzotriazol-3-yl2-[(2-aminooxazol)-4-yl] -2-Z-methoximinoacetamide. n.m.r. (CDCl₃ plusDMSO/d₆) δ3.90 (s, 3, --OCH₃), 5.95 (m, 3, the 5, 6, and 7 protons ofthe benzotriazole group), 8.45 (d, 1, the 4 proton of the benzotriazolegroup).

EXAMPLE 7

Preparation of7β-[2-[(2-aminooxazol-4-yl]-2-Z-methoximinoacetamido]-3-methylpyridinium-3-cephem-4-carboxylate

7β-Amino-3-methylpyridinium-3-cephem-4-carboxylic acid chloride (0.134g, 0.364 mmol) was suspended in acetone/water (1.6 ml/l ml) and the pHof this suspension was adjusted to approximately 7.5 by the dropwiseaddition of a 45% solution of potassium phosphate.1-(N-oxide)benzotriazol-3-yl2-[(2-aminooxazol-4-yl]-2-Z-methoximinoacetamide (0.1 g, 0.33 mmol) wasadded to the suspension and the resulting suspension was stirred in thecold for 2 hours, then the mixture was allowed to slowly warm to roomtemperature. The pH of this stirred suspension was maintained at pH 7.5by the addition of 45% aqueous potassium phosphate solution. Thesuspension was stirred overnight, at the end of which time the acetonewas removed in vacuo and the remaining aqueous phase was diluted withwater then washed with ethyl acetate. The aqueous layer was thenacidified to pH 2 by the addition of dilute hydrochloric acid, washedwith ethyl acetate and evaporated to dryness. The residue was trituratedwith methanol and filtered. Approximately 0.1 g of this residue waspurified by HPLC on a reversed phase C-18 silica gel column. The solventsystem used for this chromatography was composed of 2% acetic acid, 6%acetonitrile, and the water. Approximately 0.025 g of pure7β-[2-[(2-aminooxazol)-4-yl]-2-Z-methoximinoacetamido]-3-methylpyridinium-3-cephem-4-carboxylatewas obtained. FT-n.m.r. (DMSO/d₆) δ3.42 (m, 2, C-2), 3.80 (3, s,N-OCH₃), 5.03 (d, 1, C-6), 5.08 (d, 1, C-3'), 5.7 (d, 1, C-3'), 5.64 (q,1, C-7), 6.8 (s, 2, amino), 7.42 (s, 1, oxazole aromatic proton), 8-9.6(m, 6, amido proton and pyridinium protons).

I claim:
 1. A compound of the formula ##STR42## wherein: R₁ is hydrogen,C₁ to C₄ alkyl, a carboxy-substituted alkyl or carboxy-substitutedcycloalkyl group represented by the formula ##STR43## wherein m is 0 to3; a and b when taken separately are independently hydrogen or C₁ to C₃alkyl, or when taken together with the carbon to which they are attachedform a C₃ to C₇ carboxylic ring; R' is hydroxy, amino, C₁ to C₄ alkoxy,or --OR" where R" is a carboxy-protecting group; or R₁ is a secondaryamido group of the formula ##STR44## wherein R'" is C₁ to C₄ alkyl,phenyl or C₁ to C₃ alkyl substituted by phenyl; R₈ is hydrogen or anamino protecting group; G is chloro, bromo, hydroxy, C₁ to C₄ alkoxy,phenoxy, or a group of the formula

    --O--J

wherein J is the residue of a group forming an activated ester; or agroup of the formula

    --O.sup.⊖ M.sup.⊕

wherein M.sup.⊕ is a monovalent cation.
 2. The compound of claim 1,wherein R₁ is C₁ to C₄ alkyl.
 3. The compound of claim 2, wherein R₁ ismethyl.
 4. The compound of claim 1, wherein R₈ is hydrogen.
 5. Thecompound of claim 1, wherein R₈ is an amino protecting group.
 6. Thecompound of claim 5, wherein R₈ is chloroacetyl.
 7. The compound ofclaim 1, wherein G is hydroxy.
 8. The compound of claim 7, wherein R₁ isC₁ to C₄ alkyl.
 9. The compound of claim 8, wherein R₁ is methyl. 10.The compound of claim 9, wherein R₈ is hydrogen.
 11. The compound ofclaim 1, wherein G is a group of the formula

    --O--J

wherein J is the residue of a group forming an activated ester.
 12. Thecompound of claim 11, wherein J is ##STR45##
 13. The compound of claim11, wherein R₁ is C₁ to C₄ alkyl.
 14. The compound of claim 13, whereinR₁ is methyl.
 15. The compound of claim 14, wherein J is ##STR46## 16.The compound of claim 15, wherein J is ##STR47##
 17. The compound ofclaim 16, wherein R₈ is hydrogen.
 18. The compound of claim 1, wherein Gis C₁ to C₄ alkoxy.
 19. The compound of claim 18, wherein G is ethoxy.20. The compound of claim 18, wherein R₁ is C₁ to C₄ alkyl.
 21. Thecompound of claim 20, wherein R₁ is methyl.
 22. The compound of claim21, wherein G is ethoxy.
 23. The compound of claim 22, wherein R₈ is anamino protecting group.
 24. The compound of claim 23, wherein R₈ ischloroacetoxy.
 25. The compound of claim 22, wherein R₈ is hydrogen.